using System.Collections.Generic;
using NFreeMarker.Core;

namespace NFreeMarker.Template
{
    /**
     * Objects that implement this interface can be used as user-defined directives 
     * (much like macros). They can do arbitrary actions, write arbitrary
     * text to the template output, and trigger rendering of their nested content
     * any number of times.
     *
     * @since 2.3.11
     * @author Attila Szegedi
     * @version $Id: $
     */

    public interface ITemplateDirectiveModel : ITemplateModel
    {
        /**
         * Executes this user-defined directive; called by FreeMarker when the user-defined
         * directive is called in the template.
         *
         * @param env the current processing environment. Note that you can access
         * the output {@link java.io.Writer Writer} by {@link Environment#getOut()}.
         * @param params the parameters (if any) passed to the directive as a 
         * map of key/value pairs where the keys are {@link string}-s and the 
         * values are {@link TemplateModel} instances. This is never 
         * <code>null</code>. If you need to convert the template models to POJOs,
         * you can use the utility methods in the {@link DeepUnwrap} class.
         * @param loopVars an array that corresponds to the "loop variables", in
         * the order as they appear in the directive call. ("Loop variables" are out-parameters
         * that are available to the nested body of the directive; see in the Manual.)
         * You set the loop variables by writing this array. The length of the array gives the
         * number of loop-variables that the caller has specified.
         * Never <code>null</code>, but can be a zero-length array.
         * @param body an object that can be used to render the nested content (body) of
         * the directive call. If the directive call has no nested content (i.e., it is like
         * [@myDirective /] or [@myDirective][/@myDirective]), then this will be
         * <code>null</code>.
         *
         * @throws TemplateException
         * @throws IOException
         */

        void Execute(
            Environment env,
            IDictionary<string, ITemplateModel> parameters,
            ITemplateModel[] loopVars,
            ITemplateDirectiveBody body);
    }
}